The leukotrienes constitute a group of locally acting hormones, produced in living systems from arachidonic acid. The major leukotrienes are Leukotriene B.sub.4 (abbreviated at LTB.sub.4), LTC.sub.4, LTD.sub.4 and LTE.sub.4. The biosynthesis of these leukotrienes begins with the action of the enzyme 5-lipoxygenase on arachidonic acid to produce the epoxide known as Leukotriene A.sub.4 (LTA.sub.4), which is converted to the other leukotrienes by subsequent enzymatic steps. Further details of the biosynthesis as well as the metabolism of the leukotrienes are to be found in the book Leukotrienes and Lipoxygenases, ed. J. Rokach, Elsevier, Amsterdam (1989). The actions of the leukotrienes in living systems and their contribution to various diseases states are also discussed in the book by Rokach.
European Patent Application 488,602(ICI) discloses compounds of structure 1 as inhibitors of 5-lipoxygenase. These compounds differ from the present invention most notably in the nature of X.sup.1 of the reference structure which is defined as --X.sub.4 --CR.sub.2 -- or --CR.sub.2 --X.sub.4 -- whereas the present compounds have a carbon atom [C(Ar.sup.3).dbd.CHCO.sub.2 H] to which is attached a carboxyl-carrying chain. EP 129,906 (Hoffmann-LaRoche) describes compounds such as 2 as intermediates with no disclosed biological activity and lacking the carbinol unit of the present compounds [R.sup.1 R.sup.2 C(OR.sup.3)--]. Compounds of structure 3 are disclosed as lipoxygenase inhibitors in EP 196,184 and WO 90/01929 (Wellcome), differing from the present compounds in the nature of their X link and the substitution on their Ar unit. Compounds related to 4 are disclosed by Schrotter et al., as having anti-infective/anti-septic properties. There are structural differences from the present compounds, such as the absence of a carboxylic acid and the absence of the carbinol unit of the present compounds [R.sup.1 R.sup.2 C(OR.sup.3)--]. ##STR1##